There has been an increased interest in recent years in deploying low-power nodes, e.g., pico, micro, and femto base stations as well as relay nodes, home NodeBs/eNodeBs, relays, remote radio heads, etc., to enhance the macro network performance of the wireless network in terms of the network coverage, capacity, and service experience of individual users. With the increased interest in such deployments has come the realization that there is a need for enhanced interference management techniques to address the arising interference issues caused, for example, by the transmit power variations among different cells. In the past, such interference management techniques have not been necessary because lower-power nodes have generally been used for indoor environments, and therefore, have been isolated from most forms of interference. Thus, conventional radio resource management techniques do not consider information about the interference after suppression, referred to herein as interference suppressed information. For example, indoor environments generally experience good isolation from interference caused by macro-layer transmissions. However, lower-power nodes are now being considered for outdoor environments, and for capacity enhancement in general, where interference management is more critical.
Heterogeneous networks, where low-power nodes of different transmit powers are placed throughout a macro-cell layout to cope with nonuniform traffic distribution, have been subject to standardization in 3GPP. Deployment of such technology is effective for capacity extension in certain areas, e.g., small geographical areas with higher user density and/or higher traffic intensity known as traffic hot spots. Further, heterogeneous deployments may also be used to adopt the wireless network to the traffic needs and the environment. However, the mix of all of these different nodes introduces interaction between the cells in new ways, e.g., reuse-one networks where the inter-cell isolation is poor.
To address this interaction, some types of mobile communication systems, such as Wideband Code Division Multiple Access (WCDMA) systems, may use interference suppression (IS) to achieve better performance in terms of peak data rates, coverage, system throughput, and system capacity. Examples of commonly used interference suppressing receivers include the G-rake+ receiver, the Frequency Domain Equalizer (FDE) receiver, and the Frequency Domain Pre-Equalize (FDPE) receiver. As future wireless networks become more heterogeneous in terms of wireless devices, deployed radio network nodes, traffic demand, service types, radio access technologies, etc., incorporating such interference suppression with network management operations becomes increasingly important. However, the air interface load interaction, e.g., the effects of the interference created in one cell for the surrounding cells, becomes particularly difficult in WCDMA heterogeneous networks equipped with interference suppression receivers. Appendix A provides some details regarding existing technologies in this area.
To illustrate, consider a low power cell with limited coverage intended to serve a traffic hotspot, where the low-power cell is located in the interior and at the boundary of a specific macro cell. In this case, the low-power cell may use an interference suppression receiver, e.g., a G-RAKE+ receiver, to provide sufficient coverage for the hot spot. Surrounding macro cells interfere with the low-power cell, rendering a high level of neighbor cell interference in the low power cell that does not allow coverage of the hotspot, despite the use of an advanced IS receiver. Such interference only increases when transmissions in the low-power cells are at the maximum power level. As a result, the users of the hot spot are connected to the surrounding macro cells, which further increase the neighbor cell interference experienced by the low-power cell.
Recent work by the inventors of the present application has provided ways to estimate various types of interference suppressed information, e.g., interference suppressed neighbor cell interference. However, there are currently no provisions for signaling such interference suppressed information between an RBS and an RNC, between two RNCs, etc. Further, there are currently no provisions for radio resource management using such interference suppressed information. Thus, there remains a need for further network management options based on interference suppressed information.